subtle

adjective [原级]不易察觉的，微妙的；敏锐的，有洞察力的；灵活的，巧妙的；含蓄的，隐晦的；<古>狡猾的

A subtle person cleverly uses indirect methods to achieve something.
不露声色的 •  I even began to exploit him in subtle ways.  我甚至开始不露声色地利用他。